At work of alignment adjustment of a vehicle such as a motorcar, the vehicle must be stopped at a predetermined position on an alignment adjusting device.
As a general method for positioning the vehicle at the predetermined position on the alignment adjusting device, there is a method with a wheel stopper or a guide. In such a method, the wheel stopper is provided at a position which is standard in the longitudinal direction of the vehicle. An operator operates the vehicle and stops the vehicle while making wheels (tires) of the vehicle touch the wheel stopper, thereby positioning the vehicle the longitudinal direction. Otherwise, a guide is provided at a position which is standard in the lateral direction of the vehicle and the vehicle is stopped while arranging the tire along the guide, thereby positioning the vehicle the lateral direction.
However, the size and width of the tire is different for the type of the vehicle so that it is difficult to secure the positioning accuracy with the conventional positioning method.
As mentioned above, the stopped position of the vehicle is dispersed so that it is difficult to hold adjusting tools automatically to the adjustment portions arranged inside and outside the vehicle without touching the surrounding, whereby the adjustment work of the alignment cannot be automated. Namely, typically of the adjustment work of the alignment, for automating the work which requires adjusting tools to be held to predetermined positions from the outside of the vehicle, the stopped status of the vehicle must be detected correctly as the premise. In this case, the stopped status of the vehicle is a notion including the stopped position and stopped posture of the vehicle (that is common below).
Conventionally, for example, an art for detecting position of a vehicle is disclosed in the Patent Literature 1 shown below.
In the conventional art shown in the Patent Literature 1, an area sensor is arranged at a position through which the tire of the vehicle passes, and when the tire passes through the monitoring area, the time at which a photo detector of the area sensor is blocked and the signal is shut off is measured and inputted to a signal processor, and then the signal processor specifies the center position of the tire based on the length of the time at which the signal is shut off, whereby the position of the vehicle is detected.
However, with the art shown in the Patent Literature 1, it is difficult to detect the stopped status of the vehicle accurately.
Patent Literature 1: JP 2001-331281 A